The present study will include hand and face allograft recipients transplanted at least one year in several European institutions (Innsbruck, Lyon, Monza, Valencia): 11 bilateral hand transplantations, 4 single hand transplantations and 3 face transplantations. All the patients will undergo B cell phenotyping, TCR repertoire, molecular signature from operational tolerance and a skin biopsy with immunohistochemical staining of the specimens in order to show signs of acute or chronic rejection.